Hydraulic motor



May 13, 1941- D. JOHNSTON HYDRAULIC MOTOR Original Filed May 8, 1937 4Sheets-Sheet l May 13, 1941. D. JOHNSTON HYDRAULIC MOTOR Original FiledMay 8, 1937 4 Sheets-Sheet 3 E u 00. Z 9 m W N wfimja a a MW m f w b\IA/W m J 5 4 5 6 12 5 5 n d r 4/ 7 7 H h H 5 f- 4 a 9 FL x x I M 6-illll 4 |1 7 1 4 7 4 7/ A A i fi A 6 5 7 9% W /T W O a e 4 5 4 w 7 D.JOHNSTON HYDRAULIC MOTOR May 13, 1941.

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4 Sheets-Sheet 4 Original Filed May 8, 1937 EIZ 27/4 min.

Reissued May 13, 1941 HYDRAULIC MOTOR Douglas Johnston, Shelbyville,Ill. Original No. 2,128,048, dated August 23, 1938, Se,-

rial No. 141,441, May 8, 1937.

Application for reissue January 22, 1940, Serial No. 315,093

19 Claims.

This invention relates to certain new and useful improvements in ahydraulic motor in the form of a tramper for use, particularly in pack.-ing cotton, and has for its general object to provide a highlysimplified device of this character which shall be positive and reliablein operation and which shall use the minimum amount of oil, or otherdriving medium and in operation shall require neither a high degree ofskill nor extended previous experience for its ready and successful use.

Owing to simplicity of construction, compactness, and relative smallsize, my improved tramper may be manufactured at small cost as comparedwith other trampers now in use, and being, aside from the pressure pumpand source of fluid, entirely self-contained, it may be readilytransported from place to place without danger of breaking, or otherwiseharming it.

My improved tramper comprises a hollowpistonrod fixedly secured at itsupper end in an overhead support and having at its lower end a unitaryenlargement provided with certain ports and passages and constituting astationary piston, a floating sleeve provided with cooperating ports andslidably mounted on said piston and pistonrod, and having for itspurpose to act as a valve for automatically changing a flow of oil ateach end of the stroke so as to reverse the direction of the ram case,or tramper proper, and keep it going continuously; an outside floatingcase carrying at its lower end the tramper foot, constituting thetramper proper, and slidably mounted on said sleeve and piston-rod, anda floating plunger-valve for opening or closing certain ports to releasepressure in said sleeve and case, or to permit the same to be built up,and to prevent the escape of high pressure oil, according to itsposition.

Thus my device has but three moving parts, namely, the outer case, thesleeve and the plunger-valve, all of which are automatically operated,the sleeve and plunger-valve in part by oil pressure and in part bycontact therewith of the outer ram case, or a part carried thereby, andthe ram case solely by oil pressure produced in the same above or belowthe sleeve, according to the direction of movement to be imparted tosaid case and the tramper foot carried thereby.

I have stated that my invention is intended particularly for use inpacking cotton. I am aware that the principle of hydraulically operating a reciprocable member, such as the ram case, or tramper, of myinvention, herein described and set forth in the appended claims, isapplicable, without change of the generic principle involved, to manyother kinds of devices. I have in mind oil drilling machines, pneumaticmachines of various types, pumps, compressors, pile drivers, forginghammers, and many other types of machines, to any one of which myinvention may be applied, with or without suitable modificationsadapting it to a particular application, but without departing from theprinciple of the invention.

I wish to state further, that while the present form of inventioncontemplates the use of oil, placed under pressure by a pump, as thedriving medium for operating the tramper, other mobile mediums could beutilized for this purpose including gas, steam, air and water. Wherever,in the following description and claims, the use of oil is referred toas the driving medium, it is to be understood that such term is employedas typical of various fluids or liquids which might be employed, and isnot intended to exclude the use of steam, gas, air, or in fact, anyother mobile driving medium which it might be found could be utilized asthe driving medium for operating the tramper, or any other deviceemploying a reciprocating member.

Finally, it remains to be stated that in illustrating my invention Ihave omitted any showing of the press box into which the cotton ispacked by the tramper, or the lint slide and bat feeder commonlyassociated therewith, as these parts do not in any manner enter into theoperation of the tramper and their use and application are perfectlywell-known to those skilled in the art.

The invention is illustrated in the accompanying drawings, in Which-Figure l is a vertical sectional view of the tramper assembled:

Figure 2 is a sectional plan view taken on the line 2-2 of Figure 1;

Figure 3 is a longitudinal sectional plan view on an enlarged scaletaken on the line 33 of Figure 6 through the piston and sleeve thelatter being in its uppermost position and showing a portion of the ramcase and of the hollow pistonrod;

Figure 4 is a cross-sectional view taken on the line 44 of Figure 3,viewed in the direction of the arrows;

Figure 5 is a view similar to Figure 3 but taken on the line 5-5 ofFigure 6 and viewed in the direction of the arrows;

Figure 6 is a cross-sectional view taken on the line 68 of Figure 5 andviewed in the direction of the arrows;

Figure 7 is a central vertical sectional view on the same scale asFigure 3, taken on the line 1-1 of Figure 4 and viewed in the directionof the arrows;

Figure 8 is a cross-sectional view taken on the line 3-8 of Figure 7 andviewed in the direction of the arrows;

Figures 9, l0 and 11 are views corresponding respectively, to Figures 3,5 and '7, but showing in each View the sleeve in its lowermost position;and

Figure 12 is a cross sectional view taken on the line I2I2 of Figure 9and viewed in the direction of the arrows.

Referring now to the drawings, the numeral I indicates a hollowpiston-rod, which is fixedly secured at its upper end in a casting 2,into which it is screwed. At its lower end the pistonrod is secured intothe upper end of a stationary piston 3. Slidably mounted on this pistonis a sleeve 4 having a closed lower end 5. Piston rings 6 are interposedat intervals between piston 3 and sleeve 4. The numeral 1 indicates theram case which is mounted to slide up and down on the piston-rod I andlikewise has slidable and sealing contact with the sleeve 4. To thisend, piston rings 8'are interposed between the ram case and the sleeve.The lower end of the ram case is sealed by a plug, 9, which is weldedintothe ram case pressure tight. Mounted on the lower end of the ramcase is a rectangular tramper foot, II), which consists of a number ofboards bolted to the bottom of two parallel channel irons, I I. On topof these channel irons is bolted a fiat plate, I2, which is providedwith a central aperture through which the plug 9 and the lower end ofthe ram case may be passed in securing the tramper foot onto the ramcase. Welded between the two channel irons I I are two spreaders, I3,which are placed. so as to hold snugly between them the bottom plug 9,which is held by a pin, 9a, passing through the two Spreaders I3.

The tramper proper is supported by the sills, I4, which are in this casechannel irons. At one end the sills are bolted at the bottom to avertical channel iron, Ma, which is bolted at the bottom to the presssills, which are in turn bolted to the concrete press foundation. Theother ends of the tramper sills are bolted to the center column of thepress (not shown). This is usually a square or round steel column uponwhich the double box press revolves. The bottom of the center post orcolumn is also bolted to the press sills, mentioned above. In itsreciprocation, the ram case I is guided and kept aligned by a guide, I5,which is in turn held to the sills I4 by flat plates, I6 and I1 boltedto said sills.

The casting 2, at the upper end of the tramper,

and into which the upper end of the piston-rod is screwed, is heldrigidly by the tension angles, I8, (Figs, 1 and 2), which in turn arebolted at their lower ends to the sills I4 through plate IS. Thepiston-rod I must, of course, withstand the reaction from the ram case,due to the force exerted in packing the cotton, and also due to thedownward force caused by raising the ram case. This force is transmittedthrough the piston-rod to casting 2 and then down to the sills I4through tension angles I8.

To prevent leakage of the ram case I and piston-rod I, there is providedon the ram case a packing gland consisting of the parts indicated by thenumerals, I9, and 2|, of conventional construction and arrangement, thepart 2| being the packing.

Oil under pressure is admitted into the hollow piston-rod I through apipe, 22, (Fig. 1) screwed into casting 2 whence it passes down throughthe inside of the piston-rod. The oil is discharged through dischargepipe, 23, (Figs. 1, 3 and 7), which extends downward through piston-rodI to the piston 3, into the top of which it is screwed. To preventleakage of high pressure oil where pipe 23 passes through the top ofcasting 2, a packing gland, 24, is provided.

Slidably mounted on piston 3 above the sleeve 4 is a ring, 25, (Figs. 1,3, 5 and 7). Screwed flush by the stuffing box 20 against the top of theram case I is a sleeve, 26. The sleeve 4 acts as a valve toautomatically change the flow of oil at each end of the stroke of theram case so as to reverse its direction and keep it going continuously.In the downward movement of the ram case the sleeve 26 will engage thering 25 which will in turn engage the top of sleeve 4 to move the sleevedownward. The ring 25 merely acts as an auxiliary plunger, in connectionwith sleeve 26, this arrangement being provided in order to prevent thenecessity of having ram case I move down so far that the packing 2|would be cut by the joint between piston rod I and piston 3. In eachdownward movement of the ram. case the sleeve 26 operates to push sleeve4 down to its extreme lowermost position.

In its extreme lowermost position sleeve 4 will have opened an outlet tothe lower inside of the ram case, which relieves the pressure therein,allowing the high pressure oil being pumped into the upper chamber toraise the ram case. As soon as the ram case reaches its uppermostposition, the bottom plug 9 will have engaged sleeve 4 and shifted itback to its extreme uppermost position, in which position it will haveclosed the outlet to the lower chamber and opened a passage for the highpressure oil to be pumped into the lower chamber. At the same time, thissame passage will allow the oil in the upper chamber to also flow intothe lower chamber. Hence, the cycle of operation is completed and thetramper starts down on the next cycle. The arrangement of parts by meansof which the foregoing operation of the tramper is effected by the inletof pressure oil to the piston Will now be described, referring toFigures 3 to 11 inclusive 7 of the drawings.

In its upper portion, the piston 3 is provided with a hollow portion, orchamber, 21, (Figs. 3, 5 and '7), the wall of which is provided onopposides with ports, 28, 29 and 30, 3|, separated equal distances fromeach other. The sleeve 4, in the portion thereof occupied by the pistonrings 8, divides the ram case 1 into an upper chamber 32 (Fig. 1) and alower chamber 33 (Fig. 3) and the ports 23-3I communicate with the upperchamber 32 above the level of the top of sleeve 4 when the latter is inits uppermost position, as shown by Figs. 3, 5 and '7.

The sleeve 4 in its lower portion, that is in the part 4 thereof belowthe bearing portion containing the piston rings 8, is reduced indiameter to provide an annular space 34 between its wall and the wall ofthe ram case I. Toward the lower end of this reduced portion the wall ofthe sleeve is provided with a port 35, which is located at such distanceabove the bottom 5 as to be moved beyond the lower end of the piston 3when the sleeve is moved to its extreme lower position so as to opencommunication between the lower chamber 33 and a chamber 36 providedbetween the bottom 5 of the sleeve and the lower end of the piston 3when the bottom of the sleeve is moved downward, or away from the lowerend of the piston (Figures 9 to 11). The piston 3, below the portionthereof containing the chamber 21, is cored out to provide an outletpassage 31, the outlet pipe 23, extending through the chamber 21 at adistance from its wall, being screwed into the piston 3 at'the upper endof the outlet passage, 31, in a manner to form a continuation of saidpassage (Figures 3 and 7). At the bottom of the outlet passage 31 thewall of said passage and the body of the piston is cut through toprovide an enlarged or circumferential port, 38, (Figures 3, 4 and 7)which, when the sleeve is in its lowermost position (Figures 9 to 11)registers with a circumferential series of ports, 39, formed in the wallof the reduced portion 4 of sleeve 4 at the upper end thereof. When theports 38 and 39 are in register they establish communication from thelower chamber 33 of the ram case through the annular passage 34 to theoutlet passage 31.

To provide for the passage to the lower chamber 33 of the ram case ofpressure oil passing through the hollow piston rod 1 to the chamber 21of the piston, the latter is provided with an inlet passage, 45,extending longitudinally through the piston from the bottom of chamber21 to near the bottom of the piston where a port, 41, is providedleading from the bottom of inlet passage 4% to the outer side of thepiston (Figures 5, '7, l and 11) When the sleeve is in its uppermostposition, as shown by Figure 7, the port 4! of the piston is in registerwith the port 35 of the sleeve 4, previously referred to, which permitsthe pressure oil to pass directly from the chamber 21 through passage43, ports 4| and 35, and annular passage 34 to the lower chamber 33 ofthe ram case.

In order to control the application of the pressure oil effective withinthe chamber 35 of the sleeve, to permit, or prevent, the movement ofsaid sleeve in the downward or upward movement of the ram case, so thatsaid sleeve may function at the proper stage of said strokes to close oropen the ports controlling the application of the pressure oil to theram case, the following construction is provided, referring to Figures 3to 6, and Figures 9, l0 and 12 of the drawings:

The piston 3 is longitudinally cored from its lower end to near itsupper end to provide a cylindrical bore, 45 (Figures 4 and 12) in whichis slidably mounted a plunger-valve, indicated generally by the numeral4i (Figures 3, 5, 9 and ,10). This plunger-valve comprises, preferablyas an integral structure, a plunger-rod, 42, having at its lower. end. aplunger-valve, 43; below said valve a reduced portion, 44, and at thelower end of the portion 44 a small foot-valve, 45. The valves 43-45divide the bore 40 into an upper valve-chamber, 45, (Figures 9 and 10)and the lower valve chamber, 41, (Figures 3 and Between the valves 43and 45 the reduced portion 44 provides an annular intermediatevalve-cham- ,ber, 48. The lower end of bore 43 is closed by ascrew-plug, 49. A small longitudinal bore, 55,

extending through valve 43 from end to end thereof serves to afiordcommunication between the intermediate valve-chamber 48 and the uppervalve-chamber 46 fora purpose to be presently described. The piston 3 isfurther provided with a cored hole, 5|, extending from its under side,from the upper end of which ports, 52, (Figures 3, 5, 6, 9 and lead intothe intermediate valvechamber 48, whereby communication from sleevechamber 36 through hole 51 and ports 52 with the intermediate valvechamber 43 may be established. From the intermediate valve chamber 48ports, 53, (Figs. 3, 4, 6 and '7) communicate with the outlet passage31. Leading from the lower valve chamber 41 are ports, 54, which extendthrough the wall of said chamber (Figures 3, 6 and 9) and which, whenthe sleeve 4 is in its uppermost position, as shown in Figure 3, are incommunication with ports, 55, extending through the wall of the sleevewhereby communication may be established between the annular space 34and said ports with the lower valve chamber 41. When the plunger valve4P has been lowered, as hereinafter described, the ports 54 and 55 willbe placed in communication with the intermediate valve chamber 48 andhence with ports '52, which movement of the plunger valve occurs priorto the downward movement of sleeve 4, so that pressure oil from thelower ram case chamber 33 may pass through annular space 34 ports 55, 54and 52 through cored hole 5| to the sleeve chamber 35, thus balancingthe pressure on both sides of the sleeve. Hence, no resistance will beoffered to the subsequent downward movement of said sleeve.

In order to maintain the plunger valve 4l in its upward position priorto the time it is moved downward by contact of sleeve 26 at the upperend of the ram case I with the slide ring 25, which in turn is adaptedto engage the plunger rod 42, the small port 55 is provided whichpermits high pressure oil from the inlet passage 40 to enter valvechamber 47 and thus exert upward pressure on the bottom of the plungervalve. (See Figures 5 and 10.)

The portion of the piston 3 above the bearing portion thereof providedwith the piston rings 5 is reduced in diameter and on this reducedportion is slidably mounted the ring 25, previously referred to. Thisring is fluted on the outside to provide ports, 51, (Figures 3 and 8) toallow free passage of oil on the downward stroke of the ram case fromthe upper chamber 32 to ports 25 and into the hollow port 21 of piston3. Mounted in a circular groove provided in the interior wall of sleeve4 at its upper end is a stop ring, 58 (Figure 3), which also is adaptedto slide upon the said reduced portion of the piston. This reducedportion provides a circular shoulder, 59, which will serve to limit thedownward movement of sleeve 4 when engaged by the stop ring 58.

In order to cushion the sleeve 4 at the extreme limit of its downwardmovement, in case the tramper should be operated without packing cotton,I provide a port, 50, best shown in Figures '7 and 8, which port isrelatively wide at its upper end, and tapers to a mere slit at its lowerend. This port is provided in the wall of the inlet passage 40 and henceoil may pass throughsaid port to the annular space, 5|, surrounding thereduced portion of the piston and closed at its upper end by stop ring53. As the sleeve 4 is moved downward, the gradually decreasing area ofport offers increasing resistance to the expulsion of oil throughsaidport by stop ring 58 and causes the movement of the sleeve to beslowed down. The operation of the tramper will now be described, firstpremising that Figures 1, 3, 5 and '7, and the sectional views, Figures4, 6 and 8, illustrate the position of parts when the ram case I, sleeve4 and plunger valve 4| are in their uppermost position; while Figures 9,l0, l1 and 12 illustrate the position of parts when said elements are intheir lowermost position.

Referring now to the first-named figures of the drawings, with the portsin the position shown, oil under high pump-pressure entering the inletpipe 22 passes down through the hollow piston rod I into piston chamber21, through inlet passage 40, out of port 4| in piston, throughregistering port 35 in sleeve 4, along annular passage 34 between ramcase I and said sleeve, and into lower chamber 33 of the ram case. Atthe same time, oil, under the same pressure, is flowing out of the upperchamber 32 of the ram case through ports 28 and 3!! into piston chamber21 and in the same manner as described to the lower chamber 33 of theram case. Since on the downward stroke the high pressure oil is exertingpressure in both the upper and lower chambers of the ram case, the forcein the lower chamber tending to push the ram case 1 down, and the forcein the upper chamber tending to push it up, it will be seen that the netforce available for packing the cotton will be equal to the differencebetween the areas which are filled with oil in the upper and lowerchambers. In other words, the force pushing the rain case down will beequal to the pump pressure times the net area it acts against. The areathe pressure acts against downward is the area of the inside of the ramcase, while the area it acts against upward is equal to the same areadiminished by the area of the piston-rod l. Therefore, the net areadownward is equal to the area of said piston-rod. It follows that theforce the tramper will exert is equal to the area of the piston-rodtimes the pressure developed by the pump.

On the downward stroke there are no outlets open. This feature of theinvention reduces the quantity of oil needed to operate the tramper. Theamount of oil required to drive the tramper down is equal to the area ofthe piston-rod multiplied by the length of the stroke.

The plunger valve is held in its upper position by high pressure oilpassing through the small port 56 to valve chamber 41 from the inletport 40. At the same time pressure oil passes from the lower chamber 33of the ram case through annular space 34 and ports 55, 54 to said valvechamber. The intermediate valve chamber 48 is in communication with thecored hole in the piston through ports 52 and with the outlet 31 throughports 53. Chamber 36 in the lower end of sleeve 4 communicates throughcored hole 5| in the piston 3, and ports 52 with the intermediate valvechamber 48. This communication exists always. In this position, there isno pressure in the lower chamber 36 of sleeve 2.

The upper plunger chamber 46 has zero pressure since it communicatesthrough port 50 in valve 43 with the intermediate valve chamber 48,which is in communication with outlet 37 through ports 53.

While pump pressure acts on the upper end of the plunger rod 42 inpiston chamber 21, since the area of this plunger rod is less than thatof valve 43, there will be a net force to hold valve 3 in its upperposition.

As the ram case 1 moves downward under the pressure of oil in its lowerchamber 33, the first event occurs when sleeve 25 (Figure 1) engagesring 25 which in turn engages plunger rod 42 to move the plunger valve4| downward. To facilitate this operation I preferably secure a bar, 62,(Figure 3) to the upper end of the pressure rod by means of a bolt, 63.This bar extends clear through the walls of piston chamber 21 into ring25 to which it issecured (Figure 8). The walls of chamber 27 are slottedto allow the bar 62 to move up and down, one of these slots being shownby full lines in Figure 9 and indicated by the numeral 64. Bar 62 willthere- 'fore be engaged at opposite ends by ring 25 as the latter ismoved downward, as will be apparent from inspection of Figure 8. As theplunger valve moves down, the valve 43 will cover ports 53 before ring25 has moved down far enough to engage sleeve 4, and foot-valve 45 willfirst cover and then uncover ports 54 to place them in communicationwith the intermediate valve-chamber 48 and ports 52. At this stage, i.e., with the plunger-valve lowered to substantially the position shownin Figure 9, but with sleeve 4 in the raised position in Figure 3, thehigh pressure oil in lower chamber 33 is in communication with thesleeve chamber 36 by means of annular space 34, ports 55 and 54,intermediate valve chamber 48, ports 52 and the cored hole 5|.Therefore, the pressure inside chamber 36 is the same as outside andsleeve 4 will oiTer no resistance to being pushed down. The ring 25 nowengages the upper end of sleeve 4 and pushes the sleeve down moving port35 beyond port 4| of inlet passage 40, thereby closing port 4| andcutting off passage of pressure oil to the lower chamber 33 of the ramcase. The pressure on the lower end of sleeve 4, both inside and out, isnow the same as at the upper end, and the sleeve is therefore floating,therefore only a slight force is required to move it down, which is onlythe amount of force required to overcome a small frictional resistance.Also, except for the small force needed at first to hold downplunger-valve 4|, as explained later on, the same force is available forpacking cotton as was available at the beginning of the downward stroke,namely, the oil pressure times the area of piston rod I.

The oil .is now flowing only into upper chamber 32, and no outlets areopen. Therefore, this oil will move sleeve 4 down until port 35 insleeve 4 opens into chamber 36, Figure 9, which afl'ords another meansof allowing the oil in chamber 33 of the ram case and chamber 36 ofsleeve 4, to communicate. In this movement of the sleeve port 55 will bemoved beyond port 54, closing the latter. The down-ward movement ofsleeve 4 just described is permitted by the fact that the rare case 1moves downward simultaneously with the sleeve, but at a slower rate,increasing the length of chamber 36 to provide space for the oildisplaced by the downward travel of the sleeve. Thus, as stated, thesleeve is floating, since on its upper end, chamber 21 and ports 51;inside its lower end, chamber 36; and outside its lower end, chamber 33,all pressures are the same, and equal to the pump pressure, disregardinga slightly greater pressure in the upper chamber 21 due to thefrictional resistance offered to movement by the sleeve. The latter isnow free to move down because there is no fluid pressure or mechanicalobstruction holding it up. At this point the sleeve is merely a floatingconnection between the fluid in the upper and lower portions, 32 and 33,respectively, of the ram case. The oil pressure in the lower chamber isacting over the entire area of the inside of the ram case, while in theupper chamber the same pressure is acting only over the area of theinside of the ram case, less the area of the piston rod. Therefore, asbefore, the net force exerted by the ram is equal to the pump pressuretimes the difference between the area in the lower and upper chambers,which area is equal to the area of the piston rod. If, now, it beassumed that sleeve 4 does not move downward at this point, then the oilbeing pumped into the upper chamber 32 through hollow piston rod I, willimmediately increase in pressure andact on the upper annular end of thesleeve, forcing the sleeve down against the oil in lower chamber 33 ofthe ram case. This will cause the pressure in this chamber to riseequally (or nearly so) in amount to the rise of pressure in the upperchamber. However, the oil in the lower chamber 33 acts downward on theend of the ram case 1 on an area much larger than the annular area ofchamber 32 of the upper end of the ram case. Therefore, the ram casewill have a greater increase in force downward and will travel downward,increasing the area of lower chamber 33, allowing sleeve 4 to slidedownward. Finally, ports 39 in sleeve 4, (Figure 12), are moved intoregister with port 38 in piston 3 to relieve pressure in chamber 33 byproviding an outlet through annular passage 34, ports 33 and 38 andoutlet passage 31.

At this point, pressure both inside and outside of sleeve 4, includingchamber 33 of the ram case and chamber 36 of the sleeve has been reducedto zero, and the sleeve has reached its lowermost position. The oilpressure in the upper ram case, chamber 32 will hold sleeve 4 down inthis position and force the ram case to proceed upward, the oil in thelower chamber 33 being discharged.

At this point, it may be desirable to explain what holds the sleeve 4 inits uppermost position forsubstantially the duration of the downwardstroke of the ram case, since in both upper chamber 32 and lower chamber33 the pressures are equal and the friction of the ram case tends topull the sleeve down. This is best explained by assuming that sleeve 4does slip down closing ports 4| and 35, and cutting ofi the admission ofoil into the lower chamber 33. Now, as pressure oil is still beingpumped, the immediate efiect will be a sudden rise of pressure in theupper chamber 32. This rise of pressure in the upper chamber, whenconsidered alone, will act against the area of sleeve 4, tending to pushit down further. However, this pressure also acts against the top areaof the upper chamber 32. This will naturally tend to force the ramcaseup. The effect of this will raise the pressure of the oil in thelower chamber 33. Of course, it will not raise it nearly as high as thepressure in the upper chamber. Now, chamber 36 of the sleeve has zeropressure in it and as the area is equal to the area of the piston 3, theslight increase of oil pressure in the lower chamber 32 acts over alarge area, unopposed by pressure from the other side. Always to beconsidered is the fact that the oil in chamber 33 acts against the areaof the sleeve as well as that area equal to the piston area. The areasare so proportioned that the pressure increase in the lower chamber,(due to the increase of pressure in the upper chamber acting upon thetop of the ram case) tending to push the sleeve up against the entirearea of the inside of the ram case, of which area an amount of area,equal to the piston area, has no pressure at all acting on the otherside, pushes up on the sleeve with a greater force than the force in theupper chamber pushes down. The result is that the sleeve can not slipdown for as soon as it closes ports 35 and 4| slightly, a rise inpressure pushes it back.

I have heretofore referred to the small force need-ed at first to holdthe plunger valve down as the ram case approaches the limit of itsdownward movement. An explanation of this will now be given.

'At the completion of the downward stroke, the first event occurs whenthe plunger-valve closes ports 53, thereby closing the outlet fromsleeve chamber 36, This requires a certain amount of force, which willhave to be deducted from the force the tramper will exert for packingcotton. However, as soon as ports 53 are closed and ports 54 begin toopen, no force will be required to push the plunger-valve for theremainder of the downward stroke. The reason for this is that as soon asports 53 are closed and ports 54 begin to open, the oil pressure in theintermediate valve chamber 48 will be the same as the pressure inthelower valve chamber 41, and through the port 50 in valve 43 the uppervalve chamber 46 will also have the same pressure. Since the pressureacting against the top of plunger-rod 42 is equal to the same pressureas in valve chambers 46 and 41, all pressure will be the same and noforce will be required to hold or push down the plunger valve.

Notwithstanding the above, one is not justified, actually, in deductingthe force required for pushing down the plunger-valve from that forcethe tramper would otherwise exert. In packing cotton, the last fewinches of movement of the tramper require very great increase in force.Now at the time the force required to push down the plunger-valve isneutralized, the tramper is still over an inch from the end of thestroke. To this point to the end of the stroke, the rise in forcerequired to pack the cotton greatly exceeds the force that was requiredby the plunger-valve. This is only to say that if a maximum force of14,000 pounds is required at the end of the stroke, a force less inmagnitude by the small amount required for the plunger-valve for theduration of about one inch, when the tramper is still within severalinches of the end of the stroke, will not lessen the packing power ofthe tramper. It is also obvious that the only force necessary toovercome in pushing down the plunger-valve, is that force designed topush the plunger valve up against the resistance of gravity andfriction.

As soon as the ram case starts upward the high pressure oilcommunicating from cored inlet hole 40 through small port 56 to lowervalve chamber 41 will force the plunger-valve back into its uppermostposition, or that shown in Figure 3. Since ports 54 and 55 are closed atthis time, this high pressure oil cannot run out of chamber 41 into theannular space 34 to the lower chamber 33 and be wasted to the outlet.This is the reason ports 54 and 55 need to be closed. Also, when theplunger valve moves up it provides an additional outlet from lowerchamber 33, through the annular space 34, port 35, chamber 36, the coredhole 5|, ports 52, intermediate valve chamber 43, and ports 53, to theoutlet passage 31. However, when the sleeve is shifted upward, ports 54and 55 will open before port 35 in sleeve 4 closes communication withchamber 36, which is connected to the outlet. Therefore, there willoccur a momentary leakage of oil from inlet passage 40 through port 56to chamber 41, through ports 54 and 55, annular space 34, port 35 tochamber 36, out through the cored hole 5|, ports 52, intermediate valvechamber 48, ports 53, to outlet 31.

This leakage will only be momentary as; the sleeve 4 is moving uprapidly at this point. Also port 56 is so small that in the timeavailable no appreciable amount of oil can flow through it.

With the plunger valve in its uppermost position, as described, a meansof escape of oil from sleeve chamber 36 to outlet 31 is provided valvechamber 48, and ports 53. As the ram case nears its uppermost positionthe bottom plug 53 engages sleeve 4 and raises it. This movement of thesleeve is permitted by reason of the fact that the top of the ram caseis of larger area than that of the sleeve, as is obvious from aninspection of the drawings. Accordingly, if the oil acts upward on alarger area of the ram case than it acts down on the sleeve, the ramcase will raise the sleeve, due allowance having been made for theweight of the ram case. As the sleeve rises, it will close outlet ports38 and 39 and port 35 in said sleeve, which allowed lower chamber 33another outlet through annular space 34 into sleeve chamber 35. Theplunger valve is still maintaining an outlet from this chamber, asexplained above. Since the outlet to the lower chamber 33 is closed, andsince the oil is being pumped into the upper chamber 32 against theupper area of the ram case, the oil pressure in the lower chamber 33will build up, and with no pressure inside the sleeve, the latter willmove to its uppermost position, as has previously been explained indescribing the manner in which the sleeve was held up during thedownward movement of the ram case.

After the sleeve and ram case have been raised, in the manner justdescribed, the parts will then be in the position as shown in Figure 3and the downward movement of. the ram case under the pressure of oilwill be repeated in the manner which has been described.

From the foregoing it will be seen that I have provided an exceedinglysimple construction of tramper having, as stated, only three movingparts, and as these parts are constantly lubricated by the oil pumpedinto the tramper in the operation thereof, there is practically no weardue to friction, and as the moving parts are not mechanically connected,there is no part of the tramper which is liable to get out of order. Atthe same time, the eificiency of the device is very great, and due tothe fact that the oil in the upper chamber discharges into the lowerchamber, instead of to the outlet, the amount of oil required to bepumped to operate the tramper is reduced to the minimum.

I claim:

1. A double-acting hydraulic motor comprising a stationary piston, areciprocable cylinder cooperating therewith and providing workingchambers on opposite sides of said piston having different pressureareas, means for supplying pressure liquid to said cylinder, a sleeveslidably mounted and reciprocable on said piston and automaticallyreciprocated to cause the effective force of said pressure liquid to beexerted against the upper and lower ends of said cylinder inalternation, said piston and sleeve being provided with cooperatingports, and a valve automatically operated to control the reciprocationof said sleeve.

2. A double-acting hydraulic motor comprising a stationary piston, areciprocable cylinder slidably mounted thereon and providing workingchambers on opposite sides of'said piston having difierent pressureareas, means for supplying pressure liquid to said cylinder, a floatingsleeve slidably mounted on said piston and interposed between the latterand said cylinder, and automatically shiftable, in part by the movementof the cylinder and in part by differential pressures within thecylinder to cause the effective force of the pressure liquid to beexerted against the 21,798 through the cored hole 5! ports 52,intermediate upper and lower ends of said cylinder in alternation, and aslide valve governing certain ports in said sleeve and adapted to beautomatically reciprocated to control the movement of the sleeve at thetermination of the stroke of the cylinder in either direction.

3. A double-acting hydraulic motor comprising a stationary piston, areciprocable cylinder slidably mounted thereon and providing workingchambers on opposite sides of said piston having diiferent pressureareas, means for supplying pressure liquid to said cylinder, a floatingsleeve slidably mounted on said piston and interposed between the latterand the cylinder and automatically shiftable to cause the effectiveforce of the pressure liquid tobe exerted against the upper and lowerends of said cylinder in alternation, said piston and sleeve havingcooperating ports, and a slide valve governing certain of the ports inthe sleeve and adapted to be initially actuated by the cylinder in onedirection and to be moved in the opposite direction by pressure withinthe cylinder, said slide valve operating to control the movement of saidsleeve at the termination of the stroke of said cylinder in eitherdirection.

4. A hydraulic motor for a tramper comprising, in combination, astationary piston having an inlet and an outlet passage each of which isprovided with a port, a sleeve slidably mounted on the piston having aclosed bottom providing, with the bottom of the piston, a sleevechamber, a ram case slidably mounted on the sleeve and providing upperand lower pressure chambers, to the pressures in which said sleeve isresponsive, the upper chamber having a less pressure area than thelower, an inlet and an outlet port in said sleeve co-operating with thecorresponding ports in said piston for controlling the admission anddischarge of pressure oil to and from said lower chamber, a port in saidpiston afiording communication between said inlet passage and the upperchamber of the ram case, whereby pressure oil admitted to said inletpassage with the ram case and sleeve in their uppermost position willenter said-lower pressure chamber and force the ram case downward tocause the upper end of the ram case to engage said sleeve and,supplemented by pressure in the upper chamber, move it downward tochange the position of the ports so as to close the inlet to the lowerchamber and permit pressure oil to discharge therefrom, while pressureoil entering said upper chamber will thereafter raise said ram case andcause its lower end to engage and raise said sleeve to its uppermostposition, and means operating automatically in the described movementsof the ram case and sleeve to cause the application of pressure within,or its removal from, said sleeve chamber, to permit the movements of thesleeve.

5. A hydraulic motor for a tramper comprising, in combination, a fixed,depending pistonrod having at its lower end an unitary piston providedwith inlet and outlet passages. each having ports, a sleeve of greaterlength than the piston slidably mounted thereon, having a closed bottom,and having ports adapted to cooperate, respectively with ports of thepiston, a ram case of greater length than the sleeve slidably mountedthereon providing sealed upper and lower chambers one port in saidpiston affording communication between its inlet passage and the upperchamber of the ram case, said ram case being adapted at the end of itsupward and down- Ward movements to move said sleeve in a correspendingdirection, and. the latter being responsive to oil pressure in saidchambers, the relative disposition of the ports being such that with theram and sleeve in their uppermost position oil under pressure admittedto said inlet passage will pass into said lower chamber and force theram case downward, thereby causing said sleeve to be moved to change theposition of its ports to shut off the passage of oil to said lowerchamher and release the pressure oil therefrom, while pressure oil willenter said upper chamber and thereafter raise the ram case and cause thelatter to raise said sleeve, and means automatically operating in thedescribed movements of the ram case and sleeve to control theapplication of pressure to, or its removal from, said sleeve, to permitthe movements thereof.

6. A hydraulic motor for a tramper comprising, in combination, a fixed,depending piston-rod having at its lower end an unitary piston providedwith inlet and outlet passages each having ports, a sleeve of greaterlength than the piston slidably mounted thereon, having a closed bottom,and having ports adapted to cooperate with ports of the piston, a ramcase of greater length than the sleeve slidably mounted thereon,providing sealed upper and lower chambers, one port in said pistonaffording communication between its inlet passage and the upper chamberof the ram case, said ram case being adapted at the end of its upwardand downward movements to move said sleeve in a corresponding direction,and the latter being responsive to oil pressure in said chambers, therelative disposition of the ports being such that with the ram case andsleeve in their uppermost position oil under pressure admitted to saidinlet passage will pass into said lower chamber and force the ram casedownward, thereby causing said sleeve to be moved to change the positionof its ports to shut off the passage of oil to said lower chamber and release the pressure oil therefrom, while pressure oil entering said upperchamber will thereafter raise the ram case and cause the latter to raisesaid sleeve, and a plunger valve automatically operating in thedescribed movements of the ram case and sleeve to control theapplication of pressure to, or its removal from, said sleeve, to governthe movements thereof.

'7. A hydraulic motor for a tramper comprising, in combination, a fixed,depending pistonrod, a stationary piston secured on the lower endthereof, having an inlet and an outlet passage provided, respectively,with an inlet and outlet port, a sleeve slidably mounted on said pistonhaving a closed bottom, a ram case of greater length than the sleeveslidably mounted thereon and providing upper and lower sealed chambers,the upper chamber having a less pressure area than the lower chamber andbeing in constant communication with said inlet passage, said sleevehaving ports controlling communication of said inlet and outlet portswith said lower chamber and being itself responsive to pressures in bothof said chambers, the relative disposition of the ports being such that,with the ram case and sleeve in their uppermost position, pressure oiladmitted into said inlet passage will pass into said lower chamber andforce the ram case downward, causing its upper end to move the sleevedownward to close said inlet port while pressure in the upper chamberwill complete the downward movement of the sleeve to open said outletport, and will thereafter raise the ram case and cause its bottom toraise said sleeve, and means operating automatically in the downwardmovement of the ram case to balance pressures above and below the bottomof the sleeve to permit of its downward movement, and thereafter torelease the pressure above said bottom to permit the upward movement ofthe sleeve.

8. A hydraulic motor for a tramper comprising, in combination, a fixed,depending pistonrod having at its lower end an unitary piston providedwith inlet and outlet passages each having a port, a floating sleeve ofgreater length than the piston slidably mounted thereon, having a closedbottom providing between itself and the bottom of the piston a sleevechamber, and having ports adapted to cooperate, respectively, with theports of the piston, a ram case of greater length than the sleeveslidably mounted thereon and providing sealed upper and lower chambers,a port in said piston aifording communication between its inlet passageand said upper chamber, a valve chamber in the piston, a plunger valvemounted therein normally subject on its lower end to pressure from saidinlet passage and governing ports in said valve chamber adapted tocommunicate, respectively, with said lower chamber, said sleeve chamberand said outlet passage, a port in said sleeve controlling thecommunication of said valve chamber with said lower chamber, therelative disposition of the ports and of pressure areas being such thatwith the ram case and sleeve in their uppermost position, oil underpressure admitted to said inlet passage will pass into said lowerchamber and force the ram case downward, its upper end will move saidplunger valve downward to close the outlet port in the valve chamber andadmit pressure oil from said lower chamber through the valve chamberinto said sleeve chamber, and then move said sleeve downward to closethe inlet to the lower chamber, pressure in the upper chamber will nextforce the sleeve still lower to open the port to said outlet passage,and thereafter raise the ram case, and the plunger valve will be raisedby oil pressure to permit oil from the sleeve chamber to pass throughthe valve chamber to said outlet passage.

9. A hydraulic motor for a tramper comprising in combination, a fixed,depending pistonrod having at its lower end a piston provided with inletand outlet passages each having ports, a sleeve slidably mounted on thepiston having a closed bottom, and having ports adapted to cooperate,respectively, with ports of the piston, a ram case slidably mounted onthe sleeve providing upper and lower sealed chambers, one port in saidpiston affording communication between its inlet passage and said upperchamber, said ram case being adapted at the end of its upward anddownward movements to move said sleeve in a corresponding direction, andthe latter being responsive to oil pressures in said chambers, therelative disposition of the ports being such that with the ram case andsleeve in their uppermost position, oil under pressure admitted to saidinlet passage will pass into said lower chamber and force the ram casedownward, thereby causing said sleeve to be moved to change the positionof its ports to shut off the passage of oil to said lower chamber andrelease the pressure oil therefrom, while pressure oil entering saidupper chamber will thereafter raise the ram case and cause the latter toraise said sleeve, and a plunger valve subject on its under side to oilpressure from said inlet passage and adapted to be lowered by said ramcase in the downward movement thereof, and to be raised by oil pressurein the upward movement of the ram case, and ports controlled by saidplunger valve, whereby, in the described movements of the ram case andsleeve, said plunger valve will control the application of pressure to,or its removal from, said sleeve to permit the movements thereof.

10. A hydraulic motor for a tramper comprising, in combination, a fixed,depending rod having at its lower end a piston provided with inlet andoutlet passages each having a port, a sleeve slidably mounted on thepiston having a closed bottom, and having inlet and outlet ports adaptedto cooperate, respectively, with the inlet and out let ports of thepiston, a ram case of greater length than the sleeve slidably mountedthereon providing sealed upper and lower chambers, the upper chamberhaving a less pressure area than the lower and being in constantcommunication with said inlet passage, said ram case being adapted atthe end of its upward and downward movements to move said sleeve in 2,corresponding direction, and the latter being responsive to oilpressures in said chambers, the relative disposition of the ports beingsuch that with the ram case and sleeve in their uppermost position, oilunder pressure admitted to said inlet passage will pass into said lowerchamber and force the ram case downward, thereby causing said sleeve tobe moved to change the position of its ports to shut off the passage ofoil to said lower chamber and release the pressure oil therefrom, whilepressure oil will enter said upper chamber to thereafter raise the ramcase and cause the latter to raise said sleeve, and a plunger valvenormally responsive on its under side to oil pressure and adapted to belowered by said ram case in the downward movement thereof prior to thedownward movement of said sleeve and to be raised by oil pressure in theupward movement of the ram case prior to the upward movement of thesleeve, said plunger valve operating in its movements to control theapplication of pressure to or its removal from, said sleeve, to permitthe movements thereof.

11. A hydraulic motor for a tramper comprising, in combination, a fixed,depending pistonrod having at its lower end an unitary piston providedwith inlet and outlet passages each having a port, a sleeve of greaterlength than the piston slidably mounted thereon having a lower closedend providing a chamber between itself and the lower end of the pistonand having upper and lower ports adapted to cooperate with the inlet andoutlet ports of the piston, respectively, a ram case of greater lengththan the sleeve slidably mounted thereon, providing sealed chambersabove and below the sleeve, one port in said piston affording constantcommunication between its inlet passage and said upper chamber, said ramcase being adapted at the end of its upward and downward movements tomove said sleeve in a corresponding direction, and the latter beingresponsive to oil pressure in said chambers, the relative disposition ofthe ports and pressure areas of said upper and lower chambers being suchthat, with the ram case and sleeve in their uppermost position, oilunder pressure admitted to said inlet passage will pass into the lowerchamber of the ram case and force it downward, thereby causing saidsleeve to change the position of its ports to close the inlet to saidlower chamber while the pressure in said upper chamber will complete thedownward movement of the sleeve to open the port to said outlet passage,

and move said lower sleeve port beyond the end of the piston to permitthe pressure oil in the lower chamber of the ram case to pass throughsaid port into said sleeve chamber, and thereafter raise the ram case,and a plunger valve operating automatically in the described movementsof the parts to place said sleeve chamber in communication with saidoutlet passage to permit the escape of oil from said sleeve chamber asthe sleeve is raised.

12. A hydraulic motor for a tramper comprising, in combination, a fixed,depending piston-rod having at its lower end an unitary piston providedwith inlet and outlet passages each having ports, a sleeve of greaterlength than the piston slidably mounted thereon, having a lower closedend providing a chamber between itself and the lower end of the piston,the pressures inside and outside of which are initially equalized andhaving an inlet and outlet port adapted to cooperate with the inlet andoutlet ports of the piston, a ram case of greater length than the sleeveslidably mounted thereon, providing upper and lower sealed chambers, thelower chamber having a greater pressure area than the upper chamber, andthe latter chamber being in constant communication with said inletpassage, said ram case being adapted at the end of its upward anddownward movements to move said sleeve in a corresponding direction, therelative disposition of the ports being such that with the ram case andsleeve in their uppermost position oil under pressure admitted to saidinlet passage will pass into the upper and lower chambers of the ramcase and, due to the greater area of the latter chamber, move the ramcase downward, forcing the oil in the upper chamber to flow into saidlower chamber and, toward the termination of its downward stroke, movesaid sleeve to change the position of the ports to close the inlet tosaid lower chamber and permit oil pressure in the upper chamber to movesaid sleeve still lower to open said outlet port and move said inletport beyond the end of the piston to permit the pressure oil in thelower chamber of the ram case to pass through said port into said sleevecham ber, and a plunger valve operating automatically in the downwardmovement of the ram case to admit pressure oil to said sleeve chamberand in the upward stroke of the ram case to place said sleeve chamber incommunication with said outlet passage to permit the escape of oil fromsaid sleeve chamber as the sleeve is raised by the ram case.

13. A hydraulic motor for a tramper comprising in combination, a fixed,depending piston-rod having at its lower end a unitary piston providedwith inlet and outlet passages each having a port, a sleeve of greaterlength than the piston slidably mounted thereon having a lower closedend providing a chamber between itself and the lower end of the pistonand having an upper ou let and a lower inlet port adapted to cooperatewith corresponding ports of the piston, a ram case of greater lengththan the sleeve slidably mounted thereon, providing upper and lowersealed chambers and adapted at the end of its upward and downwardmovements to move said sleeve in a corresponding direction, and thelatter being responsive to oil pressure in said chambers, a valvechamber provided in said piston and having a port in constantcommunication with said sleeve chamber, an outlet port, and an inletport extending through the wall of said chamber, a port in said sleevein constant communication with the lower chamber of the ram case andregistering with said inlet port of the valve chamher when the sleeve isin its uppermost position, and a plunger valve slidably mounted in saidvalve chamber normally subject to oil pressure on its lower end andadapted to be forced downward by the ram case in the downward movementof the latter prior to the downward movement of the sleeve to close theoutlet port of the valve chamber and admit pressure oil through saidinlet port to the sleeve chamber and to said valve chamber above thevalve, to balance pressures on said sleeve and valve, and to be movedupward by oil pressure in the upward movement of the ram case, prior tothe upward movement of the sleeve, to permit pressure oil to escape fromsaid sleeve chamber through said outlet port.

14. A hydraulic motor for a tramper comprising, in combination, a fixed,depending, hollow piston-rod having an inlet for pressure oil at itsupper end, a piston secured on the lower end thereof having an inletpassage forming a continuation of said piston-rod and an outlet passage,an outlet pipe extending through said hollow piston-rod and of lessdiameter than the same and forming a continuation of said outletpassage, each of said passages having a port, a sleeve slidably mountedon the piston having a closed bottom providing, with the bottom of thepiston, a sleeve-chamber, a ram case slidably mounted on said sleeve andhaving its upper end sealed about said piston-rod to slide thereon, saidram case providing upper and lower pressure chambers, to the pressuresin which said sleeve is responsive, said upper chamber being in constantcommunication with said inlet passage and its pressure area beingreduced by said pistonrod below that of the lower chamber, an inlet andan outlet port in said sleeve cooperating with the corresponding portsin said inlet and outlet passages for controlling the admission anddischarge of pressure oil to and from said lower chamber, whereby, withthe ram case and sleeve in their uppermost position, pressure oil fromsaid inlet will pass to said lower chamber and force the ram casedownward to cause the upper end thereof to engage said sleeve and,supplemented by pressure in the upper chamber, move it downward tochange the position of the ports so as to close the inlet to the lowerchamber and permit pressure oil to discharge therefrom, while pressureoil entering said upper chamber will thereafter raise the ram case andcause its lower end to engage and raise said sleeve to its uppermostposition, and means operating automatically in the described movementsof the ram case and sleeve to cause the application of pressure within,or its removal from, said sleeve chamber, to permit the movements of thesleeve.

15. A hydraulic motor for a tramper comprising, in combination, a fixed,depending pistonrod having at its lower end a stationary piston providedwith inlet and outlet passages, each having a port, a sleeve slidablymounted on the piston, having a closed bottom, and having ports adaptedto cooperate, respectively, with the ports in the piston, a ram case ofgreater length than the sleeve slidably mounted thereon providing sealedchambers above and below the sleeve, the lower chamber having a greaterpressure area than the upper chamber, and adapted at the end of itsdownward and upward movements to move said sleeve in a correspondingdirection, a port in said piston affording constant communicationbetween said inlet passage and the upper chamber of the ram case, andmeans for controlling the entrance of pressure oil to and its escapefrom the sleeve chamber to govern the movements thereof, comprising avalve chamber in said piston having at its lower end a small portcommunicating with the inlet passage, at a distance therefrom an outletport communicating with said outlet passa e, a third port in constantcommunication with said sleeve chamber and a fourth port leading throughthe wall of said valve chamber, a port in said sleeve normallyregistering with said fourth port and communicating with the lowerchamber of the ram case, and a plunger valve slidably mounted in saidvalve chamber adapted to be lowered in the downward movement of the ramcase before the sleeve is lowered thereby, and to be raised by oilpressure in the upward movement of the ram case before said sleeve ismoved thereby, said valve, in its movements controlling said outletport, and passing over and beyond said fourth port in either direction.

16. A hydraulic motor according to claim 4, in which a port is providedbetween the inlet and said upper chamber which is reduced in area fromits upper to its lower end and a collar carried on the interior of saidsleeve and slidable over said piston and port, whereby in the downwardmovement of the sleeve the same will be cushioned by the increasingresistance offered by the oil forced through said port.

17. A double-acting hydraulic motor comprising a stationary piston, areciprocable cylinder co-operating therewith and providing workingchambers on opposite sides of said piston having different pressureareas, a floating sleeve slidably mounted on said piston and a slidevalve mounted in said piston but mechanically unconnected therewith,said sleeve and piston being provided with oo-operating ports and thesleeve and valve being automatically actuated upon the admission ofpressure liquid to the cylinder to cause the reciprocation of thelatter.

18. A double-acting hydraulic motor comprising a stationary piston, areciprocable cylinder co-operating therewith, and providing workingchambers on opposite sides of said piston having different pressureareas, a floating sleeve slida- 'bly mounted on said piston in anannular space between the piston and cylinder and having sealing contactwith said piston and cylinder, and a slide valve mounted in said pistonbut mechanically unconnected therewith, said sleeve and piston beingprovided with co-operating ports and the sleeve and valve beingautomatically actuated upon the admission of pressure liquid to thecylinder to cause the reciprocation of the latter.

19. A double-acting hydraulic motor comprising a stationary piston, areciprocable cylinder mounted thereon and providing working chambers onopposite sides of said piston of different pressure areas, means forsupplying pressure liquid simultaneously to both of said chambers tocause the cylinder to be moved in one direction by diiferentialpressure, and automatic means located and operated within said cylinderto shut off the flow of pressure liquid to the chamber having thegreater pressure area and permit the discharge of liquid therefrom,whereby the force of the pressure liquid in the other chamber will beexerted to move the cylinder in the opposite direction.

DOUGLAS JOHNSTON.

